1. Field of the Invention
In general, the present invention relates to water softeners and more especially to non-water dispersible sodium alumino silicate water softeners.
2. Description of Prior Art
Hard water is water that contains a high degree of calcium and magnesium ions. This hard water causes scale in power plant boilers, water pipes and domestic cooking utensils. It also causes soap precipitation producing undesirable curd and wasted soap. Water softening involves the exchange of one divalent hard ion (either calcium or magnesium) for two monovalent soft ions (such as sodium) on a resin. Typically, hard water is passed through a bed of sodium cation exchange resin and then is softened by the formula: EQU 2RNa++Ca.sup.++ .fwdarw.R.sub.2 Ca.sup.++ +2Na.sup.+
Regeneration of the exchanger usually involves passing a fairly concentrated solution of sodium chloride through the resin causing the reverse reaction of: EQU R.sub.2 Ca.sup.++ +2Na.sup.+ .fwdarw.2RNa.sup.+ +Ca.sup.++
Typically, a gallon of hard water contains greater than 5 grains of calcium carbonate (1 grain per gallon equals 0.017 grams per liter).
Ionic exchange has been used on an industrial basis since around 1910 with the introduction of water softening, using natural and later synthetic silicates. The introduction of synthetic organic ion exchange resins since 1935 resulted from the synthesis of a phenolic concentration product containing sulfonate or amine groups, which could be used for the reversible exchange of cations and anions. The period since 1940 has been marked by a rapidly increased degree of sophistication in the design of ion exchange materials with the porosity and particle size being controlled by conditions of polymerization. Physical and chemical stability have been modified and improved to the extent that the inorganic exchangers (mineral, green sand and zeolites) have been almost completely displaced by the resinous types. Unfortunately, the resin cation ionic exchangers, being organic, cause a greater ecological problem than the inorganic zeolites. Also, their cost is higher.
U.S. Pat. No. 3,985,669 shows a composition comprising a water-insoluble aluminosilicate ion exchange material, an organic surface-active agent, a minor amount of an alkali metal oxide silicate solid and sodium sulfate. Unlike the present invention, this patent teaches using the surface-active agent in forming the spray-dried granule.
U.S. Pat. No. 4,000,094 shows a composition containing a water-insoluble aluminosilicate, an organic detergent, process aids, and sodium sulfate. The processing aids are a mixture of a sodium carbonate and a water-soluble salt of an organic compound having from 1 to 6 carbon atoms.
U.S. Pat. No. 4,019,999 shows a composition containing an alkali metal silicate, an aluminosilicate, and alkali metal orthophosphate or pyrophosphate and sodium sulfate.